Replacement for NGT Command Center?

I have an NGT-18 made by JMI. The NGT Command Center is not working properly and JMI has been unable to get replacement boards. Additionally, the only upgrade option they have is to move to their Goto system but at $7500 that is far out of my price range. So right now I'm caught between a rock and a hard place without a working hand controller.

Does anyone know of a replacement controller that I could install? The NGT split ring mount has separate motors for RA and DEC and they are both working--in fact the scope will still track, albeit without any ability to correct any discrepancies.

I hope this question isn't too broad, and will be grateful for any responses or possible other fixes.